Dysagrion Scudder

Archibald, Bruce, Cannings, Robert A., Erickson, Robert J., Bybee, Seth M. & Mathewes, Rolf W., 2021, The Cephalozygoptera, a new, extinct suborder of Odonata with new taxa from the early Eocene Okanagan Highlands, western North America, Zootaxa 4934 (1), pp. 1-133 : 35-37

Genus Dysagrion Scudder

Figs. 4–6 , 14–16 .

Diagnosis (emended). Wings distinguished from those of other Dysagrionidae genera by subnodus with reverse obliquity [all others and tentative Dysagrionidae as below (where known), normal]; and from all Dysagrioninae by: from Okanopteryx , Furagrion by pterostigma long (4–7 times its width) [ Okanopteryx : 2.5 times; Furagrion : 3; not from Okanagrion : 3–4; Stenodiafanus : 4; Primorilestes : 3.5–4; Phenacolestes : 5; Dysagrionites species: unknown]; with oblique brace vein joining posterior-proximal corner of pterostigma in forewing, hind wing [not present in Okanagrion , Phenacolestes (both known from fore-, hind wings), not known in Primorilestes (fore- or hind wings?); known in Furagrion, Okanoptyeryx , Stenodiafanus ; wing region not preserved in Electrophenacolestes , Dysagrionites species]; costal space distal to pterostigma 1 cell wide [distinct from Primorilestes , Okanopteryx , Stenodiafanus : all 2; Okanagrion : 3–5; shared with Furagrion , Phenacolestes : 1; Electrophenacolestes , Dysagrionites species: not known]; IR2 origin between RP1-2, RP3-4, closer to RP3-4, connected to RP1-2 notably more distally than to RP3-4 [other genera: origin close to or on RP1-2 (some Okanagrion ), or between RP1-2, RP3-4 as in Dysagrion (all others), but connected with RP1-2 similar level as RP3-4]; MA linear from quadrangle to zigzagged roughly mid-wing or further, linear again near, to margin [ Furagrion : similar (but differs by distinct curve beyond mid-wing); Phenacolestes : very slightly zigzagged or not in mid-portion; Primorilestes , Okanagrion : not zigzagged; Okanopteryx , Stenodiafanus , Dysagrionites species: linear to mid-wing, somewhat to strongly zigzagged to margin (in portions known); MA, MP close, 1–2 cells apart at margin [distinct from Electrophenacolestes , Furagrion , Primorilestes , Okanagrion , Phenacolestes : widely separated; not clearly distinct from Okanopteryx , Stenodiafanus , difficult to be sure of identity of MA near margin by strong zigzag, probably separated by two cells; Dysagrionites species also difficult, perhaps one cell]; CuA increasingly zigzagged distal to level of nodus [distinct from Furagrion : slightly zigzagged distal to about level of origin of RP2; Phenacolestes : very slightly zigzagged in parts; Electrophenacolestes , Primorilestes , Okanagrion : linear or only very slightly zigzagged; not clearly distinct from Okanoptyeryx, Stenodiafanus : zigzagged to various degrees distal to about mid-wing]; CuA–A space 4 cells wide [separated from Furagrion : 2; Stenodiafanus : 2 (most likely, wing incomplete); Dysagrionites delinei : 3; Dysagrionites sp. A: 2; Dysagrionites sp. B: probably 3 but unclear; not separated from Phenacolestes : 4; Primorilestes : 3–6; Okanagrion : 4–7; Okanopteryx : 2–4; not distinct from Electrophenacolestes : 4 except 5 in one column]; further from Electrophenacolestes by shorter petiole; further from Primorilestes by no linear intercalary veins in CuA–A space. Postnodal, postsubnodal crossveins not aligned at least in proximal half [separated from Stenodiafanus , Okanopteryx , Primorilestes violetae , Electrophenacolestes , Furagrion : all aligned or somewhat so in proximal half; not distinct from Phenacolestes , Primorilestes madseni , Okanagrion : all not]. Separated from Valerea (tentative Dysagrioninae ) by no linear supplementary sector between RP1, IR1 [ Valerea : with such sector]; by one cell wide in costal space distal to pterostigma [ Valerea : up to 5]. Most easily separated from other genera regarded here as possible Dysagrionidae as follows: from the Chickaloon specimen ( Garrouste & Nel 2019) by CuA increasingly zigzagged from level of nodus [linear at least to well past level of origin of IR1 (distal-most portion not preserved)]; MA, MP close [widening in distal-most preserved portion]; from Thanetophilosina by proximal side of quadrangle more than half length of distal side [less than half], IR2 originates between RP1-2, RP3-4 [originates on RP1-2]; from NHMUK I.9866/I.9718 by origin of RP3-4 [distinctly closer to subnodus]; from cf. Dysagrionidae genus A, species A ( Petrulevičius et al. 2008) by hyaline membrane [preserved portion infuscate except apex distal to pterostigma], by MA zigzagged mid-wing, CuA zigzagged distally [both linear to margin].

Discussion. Dysagrion fredericii was designated the type species of Dysagrion by Scudder (1878). His diagnosis of the genus distinguished it from Philogenia Selys , a genus currently in need of revision ( Garrison et al. 2010). Philogenia had been placed in the polyphyletic Megapodagrionidae , which was recently divided into several families ( Dijkstra et al. 2014), including the Philogeniidae , where it now resides. We, therefore, provide an emended diagnosis of Dysagrion , above.

An oblique brace vein between RA and RP1 at the posterior-proximal corner of pterostigma is seen in the fore- and hind wings of D. pruettae ( Figs. 17 , 18 ), and in the wings of D. lakesii ( Fig. 5 , slightly, but distinctly oblique), D. fredericii (see Scudder 1890 plate 6 Fig. 9 ), D. packardii (a portion preserved, but distinct: Fig. 4 , redrawn from the original by Scudder 1890 plate 6 Fig. 3 ).

The subnodus appears to be of reverse obliquity in one specimen of Okanagrion hobani , paratype 1, however, given that all other of its numerous specimens have normal obliquity, we consider this adventitious in this individual.

Figures

FIGURE 3. Phenacolestes parallelus. A, specimen YPMIP-220974 of the Yale Peabody Museum; B, drawing from A, photograph provided by Peabody Museum personnel; C, holotype, UCM-4503 of the University of Colorado (Boulder) paleontology collections; D, drawing of C, photograph provided by University of Colorado personnel; E, UCM-4545, University of Colorado (Boulder). A–D to scale, E to scale, both scale bars 5 mm.

FIGURE 4. Dysagrion packardii cotype MCZ 4656 (Packard number 252): A, drawing; B, photograph; C, holotype (Packard number 146) redrawn from Zittel (1885: his Fig. 979), also redrawn by Scudder (1890: his plate 6, Fig. 3). A, B drawn from a photograph supplied by MCZ personnel. All to scale, 5 mm.

FIGURE 5. Dysagrion lakesii Scudder type specimen MCZ 4101 (Packard number 259, not previously illustrated): A, photograph; B, drawing from a photograph supplied by MCZ personnel. Both to scale, 5 mm.

FIGURE 6. Dysagrion fredericii Scudder’s number 4167/4168 (now MCZ numbers 381A, B “type”): A, photograph; B, drawing from a photograph supplied by MCZ personnel. Both to scale, 5 mm.

FIGURE 9. Wing drawings of: Valerea multicellulata redrawn from Fig. 1 of Garrouste et al. (2017); Chickaloon Formation (Alaska) specimen redrawn from Fig. 3 of Garrouste & Nel (2017); cf. Dysagrionidae gen. et. sp. A redrawn from Fig. 4 of Petrulevičius et al. (2008) (there as “Megapodagrionidae gen. et. sp. A”); Thanetophilosina menatensis redrawn from Fig. 21 of Nel et al. (1997); NHMUK I.9866 (Isle of Wight) redrawn from Fig. 28 of Nel & Fleck (2014); Palaeodysagrion youlini redrawn from Fig. 2 of Zheng et al. (2018); Electrodysagrion neli redrawn from Fig. 2 of Zheng et al. (2019); Burmadysagrion zhangi redrawn from Fig. 3 of Zheng et al. (2016a). To associated scales, all 5 mm. Asterisks indicate quadrangles.

FIGURE 14. Tree resulting from parsimony-based analyses for Analysis 1: Tarsophlebiidae, the suborders of Odonata and former members of Dysagrionidae (Burmadysagrion, Electrodysagrion, Paleodysagrion). One single most-parsimonious tree (MPT) based on 23 continuous and 79 discrete characters. Symmetrical resampling values Ξ70 are labelled at the nodes.

FIGURE 15. Tree resulting from parsimony-based analyses for Analysis 2 (relationship Whetwhetaksidae to confirmed families of Cephalozygoptera). One single most-parsimonious tree (MPT) based on 23 continuous and 79 discrete characters. Symmetrical resampling values Ξ70 are labeled at the nodes.

FIGURE 16. Dysagrion pruettae, new species holotype, SR 13-005-012. A, photograph; B, drawing. Wings and labels (FW, forewing; HW, hind wing) colour-coded to match Figs. 17 and 18. Both to scale, 5 mm.

FIGURE 17. Dysagrion pruettae holotype, SR 13-005-012.A, drawing of forewing (FW); B, drawing of hind wing (HW). FW, HW label colours refer to those in Fig. 16. Both to scale, 5 mm.

FIGURE 18. Dysagrion pruettae holotype, SR 13-005-012.A, drawing of forewing (FW); B, drawing of hind wing (HW). FW, HW label colours refer to those in Fig. 16. Small, blue arrows indicate supplementary sectors. Both to scale, 5 mm.